The United States continues to struggle with a major opioid crisis. This is a critical issue for state Medicaid programs as rates of opioid use disorders (OUD) in the Medicaid population are almost twice as high as the general population. Nearly 40% of people with OUD have Medicaid. Evidence-based treatments for OUD, including the three FDA-approved medications, exist but are underutilized. Barriers to access and retention in treatment are numerous and complex, including stigma, provider capacity and health insurance policies. Federal and state governments regulate Medicaid Health Plans (MHPs); however the plans have discretion in several areas including coverage, utilization management, network management, provider payment and innovative policies. Plan policies directly affect individual access both through coverage and through provider willingness to offer services, given lack of coverage, administrative headaches from utilization management requirements and low payment rates. Despite the opioid crisis, there is almost no information or transparency on MHP polices related to opioid treatment services. The proposed study aims to systematically examine delivery and management of OUD treatment in MHPs, an under-explored level where important decisions are made. We will conduct a national survey of MHPs and link their responses to national data on health plan quality and to patient-level Medicaid data from three states in order to examine outcomes. The specific aims are: Aim 1. Describe Medicaid health plan OUD treatment policies (e.g. coverage requirements, utilization management, network design, payment, and innovative care approaches) across MHPs that contract with 50 states and the District of Columbia and identify state policies, market and plan characteristics associated with OUD treatment policies. Aim 2. Evaluate the relationship between Medicaid health plans? OUD treatment policies and plan-level rates of enrollee access to and quality of OUD treatment. Aim 3. Evaluate the relationship between Medicaid health plans? OUD treatment policies and patient-level outcomes of OUD treatment (e.g. pharmacotherapy duration, overdose). The study team is uniquely qualified for this project and will leverage expertise developed in four previous NIDA and NIAAA-funded commercial health plan surveys of delivery and management of behavioral health services and 2 previous NIDA-funded Medicaid studies. Findings will provide valuable information regarding access to and effectiveness of OUD treatment under Medicaid plans. This information can be used by plan administrators as they develop and implement plan policies, state Medicaid directors as they contract with and regulate MHPs and federal policy makers making determinations about use of Medicaid waivers and other efforts to address OUD in the US, to help stem the tide of OUD and its often-deadly consequences.